1. Field of the Invention
The present invention is related to the field of vending machines and, more particularly, to a frozen product vending machine with improved storage and delivery capability.
2. Description of the Related Art
Frozen food products stored for future consumption are sensitive to their temperature history. Ice cream in particular will degrade in texture and flavor when exposed to temperature variations which exceed a specified storage range over time.
Some frozen food vendors on the market use an upright style freezer, i.e., one having a vertically hinged door. Such freezer styles have advantages in that most of the interior space can be used for product storage, and the forced convection systems used make automatic defrost possible. There are significant disadvantages with the upright style, however. Because cold air is very heavy as compared to warm air, much of the cold air within the refrigerated space is replaced by warm air when the door is opened. This exposes stored products to high temperatures which degrades the product quality. In addition, each time an automatic defrost cycle is initiated, the product is exposed to higher than desired temperatures and this cyclic variation also results in product quality degradation.
Upright freezer configurations normally deliver product through a port located at the lower section of the freezer compartment. As with the opening of the freezer door, opening of the port to deliver the product to the customer allows cold air to escape from the freezer and be replaced with warm air. As a result, a substantial heat gain is produced, imparting thermal shock to the product. Condensation and subsequent freezing also results in the build-up of ice on the delivery port mechanism and throughout the freezer.
As an additional problem, because the delivery port is located a substantial vertical distance from where the frozen products are actually stored, impact damage occurs when the product is dropped. This is very undesirable, particularly since many frozen confections include very thin shells of chocolate, cone and the like which are easily broken upon impact with a hard surface.
One solution for the problem of air temperature transfer during door opening is a chest style freezer having a horizontally hinged door. With this design, the chest acts as a “pool”, holding the heavier cold air in place when the access door is opened. Drawbacks, on the other hand, include the fact that a chest-style freezer is not easily defrosted on an automatic basis, allowing ice to build over time and requiring manual removal. Furthermore, in a vending application, a chest does not easily accommodate a package delivery mechanism. Known configurations of chest freezer vending machines, such as that shown in U.S. Pat. No. 6,253,955 to Bower, often have external vending mechanisms which seriously reduce the available capacity of the vending machine for a fixed exterior size.
Capacity has been a problem with many different package delivery mechanisms. In a conventional “pick and place” mechanism, the dimensions of an axis must at least equal the total desired travel. Any extensions required, such as to reach into a space not permitted by the dimensions of the axis drive and bearing dimensions, must be added to the basic axis dimension. For a device that must reach into a bin, which may have small length and width dimensions as compared to the depth dimension, the overall length of the axis mechanism can be quite large. In that most vending machines have exterior size limitations, the size constraints for a machine using a pick and place mechanism to select a product from a storage bin for ultimate delivery to a customer make a practical design very difficult.
In addition, according to conventional product delivery mechanisms, the product is delivered to the customer by moving along the X and Y axes to a position over a chute leading to a delivery port located toward the lower section of the machine. The product is then dropped into the chute and delivered to the customer through the port. Delivery in this manner requires a port depth large enough to accommodate the width dimension of the product, thus consuming a large portion of the interior space of the vending machine. As an alternate, the product may be forced to do a flip as it falls toward the delivery location; this action tends to break a fragile product.
A need exists, therefore, for a means of operating along the vertical or “Z” dimension in a compact manner. One known design for such a device, disclosed in U.S. Pat. No. 5,240,139 to Chirnomas, uses a self-storing extension hose with a cable lifting drive in an attempt to minimize the length of the vertical axis. The problem with this configuration lies with the minimum overall length of the hose in its retracted position. A commercial design using such a retrieval mechanism wastes an unacceptably large portion of the available vending cabinet space.
In summary, a need exists for a frozen product vending machine which overcomes problems in the art including damage to the frozen products from temperature variation, damage to the frozen products from being dropped during dispensing to a customer, and inefficient use of vending machine storage space.